Android 6.0 - Download file to external storage without asking for permission

I have a superuser access on my device. I used this function very successfully to download and update my application programattically, but since android 6.0 this function stopped working (because of new type of permission requests).

My question is: since I have superuser access on my rooted device, how can edit my function so I can download the external file on the sdcard without asking for permission from user?

here is the function I use to update the app:

public class UpdateAppZ extends AsyncTask<String,Void,Void>{
private Context context;
public void setContext(Context contextf){
context = contextf;
}

@Override
protected Void doInBackground(String... arg0) {
try {
URL url = new URL(arg0[0]);
HttpURLConnection c = (HttpURLConnection) url.openConnection();
c.setRequestMethod("GET");
c.setDoOutput(true);
c.connect();

String PATH = "/mnt/sdcard/Download/";
File file = new File(PATH);
file.mkdirs();
File outputFile = new File(file, "update.apk");
if(outputFile.exists()){
outputFile.delete();
}
FileOutputStream fos = new FileOutputStream(outputFile);

InputStream is = c.getInputStream();

byte buffer = new byte[1024];
int len1 = 0;
while ((len1 = is.read(buffer)) != -1) {
fos.write(buffer, 0, len1);
}
fos.close();
is.close();

Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setDataAndType(Uri.fromFile(new File("/mnt/sdcard/Download/update.apk")), "application/vnd.android.package-archive");
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK); // without this flag android returned a intent error!
context.startActivity(intent);


} catch (Exception e) {
Log.e("UpdateAPP", "Update error! " + e.getMessage());
}
return null;
}
}


and call:

UpdateAppZ atualizaApp = new UpdateAppZ();
atualizaApp.setContext(getApplicationContext());
atualizaApp.execute("http://85.118.98.251/misho/app-debug.apk");


3 Answers
3

No you can not do that as from Android 6.0 You need to ask for dangerous permissions at runtime.

Because If the device is running Android 6.0 (API level 23) or higher,
and the app's targetSdkVersion is 23 or higher, the OS will enforce
the app to request permissions from the user at run-time.

Weather you have root access or not.

Source:
https://developer.android.com/guide/topics/security/permissions.html
https://developer.android.com/training/permissions/index.html

Download to getExternalFilesDir(). No permission needed while other apps have access.

getExternalFilesDir()

https://stackoverflow.com/a/51112708/4650581

You can use getExternalFilesDir if you want to save file without any permission.
As stated in the documentation:

getExternalFilesDir

getExternalFilesDir

Added in API level 8

API level 8

File getExternalFilesDir (String type)

File getExternalFilesDir (String type)

Returns the absolute path to the directory on the primary
shared/external storage device where the application can place
persistent files it owns. These files are internal to the
applications, and not typically visible to the user as media.

This is like getFilesDir() in that these files will be deleted when the
application is uninstalled, however there are some important
differences: Shared storage may not always be available, since
removable media can be ejected by the user. Media state can be checked
using getExternalStorageState(File). There is no security enforced
with these files. For example, any application holding
WRITE_EXTERNAL_STORAGE can write to these files.

getFilesDir()

getExternalStorageState(File)

WRITE_EXTERNAL_STORAGE

If a shared storage device is emulated (as determined by isExternalStorageEmulated(File)),
it's contents are backed by a private user data partition, which means
there is little benefit to storing data here instead of the private
directories returned by getFilesDir(), etc.

isExternalStorageEmulated(File)

getFilesDir()

Starting in KITKAT, no permissions are required to read or write to the returned path; it's always accessible to the calling app. This only applies to paths generated for package name of the calling application.

To access paths
belonging to other packages, WRITE_EXTERNAL_STORAGE and/or
READ_EXTERNAL_STORAGE are required. On devices with multiple users (as
described by UserManager), each user has their own isolated shared
storage. Applications only have access to the shared storage for the
user they're running as.

WRITE_EXTERNAL_STORAGE

READ_EXTERNAL_STORAGE

UserManager

The returned path may change over time if
different shared storage media is inserted, so only relative paths
should be persisted.

https://developer.android.com/reference/android/content/Context#getExternalFilesDir(java.lang.String)

This link may be useful:

Save files on device storage

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